Apparatus for distillation



9 4-. G. B. c QBRouGH 1,980,612

APPARATUS FOR DI STILLAT ION Filed July 7. 1931 Witness Ind/6122507" Patented Nov. 13, 1934 UNITED STATES APPARATUS FOR DISTILLATION George B. Coubrough, Long Beach, Calif., as-

signor to The Lumrnus Company, New York, N. Y., a corporation of Delaware Application July 7, 1931, Serial No. 549,130

1 Claim.

The present invention relates to methods and apparatus for distillation and more particularly to methods and apparatus of the type disclosed in my copending application Serial No. 422,344, filed January 21, 1930.

The above-mentioned co-pending application describes a process of distilling heavy oils by heating the oils, introducing them into a vaporizing zone, and providing an additional heat storage medium to prevent excessive depression of temperature in the vaporizing zone. The preferred method of introducing the heat storage medium is by continuous recirculation of the residual product. The invention is particularly useful not only for obtaining a good yield of high quality distillate, but also for obtaining a high quality product. In the case of 'oils having asphaltic bases, an asphalt of exceptional grade may be obtained.

One object of the present invention is to provide improvements in the method and apparatus of my prior application, particularly with a view to economy and facility of operation.

Another object of the present invention is to provide a method of distilling heavy oils to permit more convenient dewaxing than by existing and expensive methods.

With the above objects in view, one feature of the present invention contemplates flash vapori-. zation of the heated oils, stripping of the residue, and recirculation of unstripped or partially stripped residue to the heater to act as a heat storage medium for effecting distillation of the overhead oils. In this feature, the present invention is distinguished from the invention of my co-pending application, in which the recirculated heat storage medium comprises the stripped residue. According to the present invention, the desirable result of complete recovery of oils is at-' tained, and a considerableeccnomy, both in the apparatus and in the operation thereof is effected.

Another feature of the invention contemplates recovery of the entire lubricating stock as a single overhead distillate. It is usual in distilling operations to obtain the lubricating stock as two products, namely, a pressible wax distillate, and a heavy wax distillate, the former containing pressible or crystalline Wax, and the latter an amorphous wax. The amorphous wax may be removed from the heavy wax distillate by centrifuging, but thecrystalline wax is not subject to removal by centrifuging but must be treated by chilling and pressing; It has been found, however, that if a sufficient body of amorphous wax is contained in the oils with pressible wax, the entire body of wax is amenable to removal by centrifuging. The necessary content of amorphous wax, however, is not ordinarily obtainable by existing methods because of the loss of the heavier lubricating components in the residue. According to the present invention, the stripping of the oils practically down to asphalt through the addition of a heat storage medium to the original mixture assures a sufficient quantity of amorphous wax in the single overhead distillate to per-v mit entire wax removal by a single centrifuging operation. The de-waxed distillate may be refined, treated or cut in any suitable manner to obtain any desired lubricating products.

Other features of the invention consist of cer-' tain novel features of construction and modes of operation hereinafter described and particularly defined in the claim,

The drawing is a diagram of the preferred form of apparatus for practising the present invention.

The invention is herein illustrated and described as embodied in a method and apparatus for ob-v taining asphalt and a single lubricating oil fraction from asphaltic petroleum bottoms or reduced crude. The reduced crude comprises a crude mixture from which the lighter fractions, such as gasoline and kerosene, have been removed, leaving a mixture of the gas oil and lubricating components and asphalt. The gas oil is obtained as a distillate. The entire body of lubricating stock is obtained as another distillate," as distinguished from the usual process of recovering the lubricating stock in two separate fractions, namely, a heavy wax distillate and a light wax distillate. The asphalt is obtained as a heavy residue, containing practically none of the lubricating values of the oils. The apparatus shown in the drawing comprises a heater 2 to which the reduced crude is continuously fed through a supply line 4 by a pump 6. v The heated mixture passes from the heater through a pipe 8 into a vaporizing section 10' of a column 12. The pipe 8 delivers onto a collecting deck 14 having a baflie 16 which permits accumulation of a body of oil on the deck. An overflow pipe 18, the top of which is at a level above the deck 14, discharges into a stripping section 20 which has a plurality of contact decks 22 illustrated as being of'the conventional boiling'cap type. Steam for stripping the residue is introduced through a pipe 24 near the bottom of the stripping section. The residual product (asphalt) is withdrawn from the bottom of the column through a draw-off pipe 26.

Leading from the deck 14 is a draw-off pipe 28 for the purpose of recirculating a part of the unstripped residue. The pipe 28 connects with a pipe 30 which leads to the inlet of the pump 6.-

Thus, material collected on the deck 14 is'con The distillate vapors rising from the section 34 are rectified and condensed. The vapors are 'condensed to form two products, namely, an overhead gas oil product and a lubricating stock product, the latter containing all the components usually contained in both the heavy wax distillate and the light wax distillate of usual methods.

' To these ends, the column is provided with a rectifying section 42 having a bottom collecting deck 44 andla plurality of contact decks 46. The .collecti'ng deck 44 has a .vapor pipe 48v leading to the upperdecks and an overflow pipe 50 to pass liquid into the section 34. A draw-off 52 connected with the deck 44,'permits Withdrawalof the lubricating stock. The overhead gas oil vapors, rectified in the section 42,. are condensed in a condenser 54, the oils and water are separated in a decanter 56, and condensate oils are returned to the column as reflux through a pipe 58. The gas oil product is obtained through a pipe 60. The column maybe maintained under vacuum by any suitable means connected to the decanter at 61.

In operation, the oil mixture is heated in the heater 2 and is passed directly into the deck 14 of the column. Immediately upon entering the column, a considerable portion of the oil components flashes into vapor. The residue, as it builds upon the deck l4, continuously overflows through the pipe 18 into the stripping section, where it is subjected to a countercurrent of steam for vaporizing or stripping the remaining oil components from theasphalt. The material collecting on the deck 14 comprises the asphalt from which the 4 greater part of the heavier oil constituents have been vaporized. This. material, which maybe termed unstripped or partially stripped residue, has a high heat storage capacity, and by continuousrecirculation through the heater 2, it

- provides for carrying sufficientheat-into the vaporizing zone to prevent excessive depression of temperature upon flashing of the vapors, and

thereby assures a high degree of flash vaporization of the volatile components.

In the co-pending application above referred to, the completely'stripped residue is recirculated from the bottom of the column. Recirculation,

according to the present invention, directlyirom the deck 14, is preferred,.however, for the following reasons2-in the first place, the material second place, the recirculated medium may be handled more easily through thewpipe 22 and-the pump .24, a feature 'ot-especial importance when the process is employedfor obtaining high grade asphalt. If the asphalt werecompletely stripped before recirculation, precautions might be necessaryto prevent solidification in the pipe, The

efiiciency of the process is in no .way "reduced but is, in fact, improved by recirculating unstripped residue. a

3 The vapors from the vaporizing zone, as well as those stripped from'the residue in the strip ping zone, pass upwardly through the-entrainment catching zone 34 and the rectifying zone 42 In the zone 34, the counter flow ofrefiux 'Wax, distillate.

liquid serves the double purpose of removing entrainment and rectifying the vapors. The liquid is collected on the deck 38 and is immediately recirculated. This is an important feature of the invention, because it prevents passage of the relatively cool reflux into the vaporizing zone which would materially cool the charge and therefore reduce the flash vaporization. According to the present invention, this reflux is returned directly to the heater.

If only asingle distillate product is desired, the draw-off 52 may be omitted, and the sections 34 and 46 may be considered as combined in a single rectifying and entrainment catching section. It is in the embodiment described herein, however, that the features of the invention become most important, because the removal of a side product necessitates the use of a considerable quantity of reflux, some of which must be permitted to pass downwardly. into the zone 34. This quantity of reflux is greater than that required merely for the purpose of knocking down entrainment, and would, if permitted to pass into the vaporizing zone, cause too great a reduction in temperature. 7

In distillation of asphaltic bottoms containing gas oil and lubricating stock, the gas oil is recovered at and the entire body of lubricating stock at 52. The lubricating stock contains a mixture of the components usually recovered as two separate distillates, namely, a light or crystalline wax distillate and a heavy or amorphous Whereas in prior methods, the two distillates must be dewaxed by different processes, the recovery of the entire lubricating stock as a single distillate @Dermits dewaxing of the whole bythe centrifugal process. Dewaxing by a single operation, however, is possible only when the stock contains a large quantity of amorphous waxcomponents, that is :to say, i

it is necessary to vaporize practically all of the oil components, leaving a substantially clear asphaltic residue. This is accomplished in the present invention by providing a heat storage medium in mixture with the original bottoms in sufficient quantity to prevent excessive lowering of the sensible heat content on vaporization of the oils in the vaporizing zone. As a result, a lubricating stock dewaxable by a single operation is obtained. The stock, after dewaxing, may then be cut or refined in any desired manner. I

Although the invention has been described as embodied ina process for treating asphaltic oils, it is'to be understood that it may be applied to the treatment of any materials, regardless of the nature of the residue.

Having thus described the invention, what is claimed is: V

An apparatus for continuously distilling petroleum oils containing asphalt having, in combination, a column having a stripping section, a collectingdeck at the top of the stripping section, a heater for; heating the oils and asphalt together inthe liquid phase, a :feed line to the heater, means 'for discharging oils from the heater onto the collecting deck, a GIHW Ofi Pipe leading from the collecting deck, :a "pump for pumping material from the collecting deck to the 1 feed line, a'steam admission pipe atthe bottom of the column, and an overflow pipe for carrying residue from the collecting deck downwardly in countercurrent with-the steam.

GEORGE E. COUBROUGH. 

